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Thread: A jet plane on a large treadmill
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12-15-2005, 01:15 PM #51
I give up.
Last edited by Beaver; 12-15-2005 at 07:26 PM.
You are what you eat.
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There's no such thing as bad snow, just shitty skiers.
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12-15-2005, 01:16 PM #52Originally Posted by Beaver
The treadmill speed is DIRECTLY relavent to the forward progress of the plane. Simple logic would tell you that if the treadmill were going *faster* than the forward movement of the plane, the plane would fall off the BACK of the conveyor.
Test your theory by going to any gym with a treadmill. Turn it all the way up. Now, step onto the treadmill & report back to us the following:
1.) Whether or not the conveyor speed is relevant.
2.) Your hospital room info.
We've got to pause and ask ourselves: How much clean air do we need? ~ Lee Iacocca
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12-15-2005, 01:16 PM #53Originally Posted by BeaverI've concluded that DJSapp was never DJSapp, and Not DJSapp is also not DJSapp, so that means he's telling the truth now and he was lying before.
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12-15-2005, 01:16 PM #54Originally Posted by cj001f
45678You are what you eat.
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There's no such thing as bad snow, just shitty skiers.
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12-15-2005, 01:17 PM #55Originally Posted by cj001f
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12-15-2005, 01:19 PM #56Registered User
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Originally Posted by BeaverElvis has left the building
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12-15-2005, 01:20 PM #57
Many years ago, a friend of mine was on the road show for his company's IPO. Because they had meetings in three different cities on the same day, they chartered a Lear 35. In one of the cities, the humidity was very high when they landed, so the plane's windows fogged up and the pilots drove off the taxiway. The plane was stuck.
My friend, sitting in the back of the plane with a couple of highly paid investment bankers, heard one of them say to the other "I think the wheels are spinning."
So for those of you who disagree with Beaver, you'll be pleased to know that - despite your appalling ignorance of physics - you're not too dumb to land a lucrative job on Wall Street.
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12-15-2005, 01:24 PM #58Originally Posted by Beaver
This is hilarious... but I feel your frustration Beaver. I'll admit I've been on the wrong side of logic before but was absolutely positive I was right only to later realize I wasn't. However, this will go on your permanent record.
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12-15-2005, 01:31 PM #59Originally Posted by Beaver
Let's put me in a wheelchair to eliminate the complications of biomechanics.
Now, I'm sitting in a wheelchair, with a rope, pulled by you.
The treadmill runs so that my wheelchair speed doesn't increase in the room.
You pull.
The treadmill pulls back.
I don't move.
The wheels spin.It's idomatic, beatch.
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12-15-2005, 01:33 PM #60Registered User
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Originally Posted by CornholioElvis has left the building
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12-15-2005, 01:33 PM #61
Holy shit!!! I can't even believe the fucking carnage I'm reading here. Beaver is correct. Those of you who disagree are mentally retarded. Seriously. This is not a difficult problem. If anyone really, really believes that Beaver is wrong then I'll bet you a large sum of money that he is in fact correct. Then I'll get the video camera, a model rocket engine, and a toy plane and go to the gym.
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12-15-2005, 01:34 PM #62who guards the guardians?
- Join Date
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Why do aircraft carriers have slingshots?
Does light speed exist in absolute darkness?
Compared to all knowledge and wisdom to be acquired in a lifetime, what's a few IQ points between friends?I'm just a simple girl trying to make my way in the universe...
I come up hard, baby but now I'm cool I didn't make it, sugar playin' by the rules
If you know your history, then you would know where you coming from, then you wouldn't have to ask me, who the heck do I think I am.
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12-15-2005, 01:34 PM #63
Everyone pay attention.
Imagine the treadmill is connected to the back of a plane, so that when the plane goes forward, the treadmill moves backward at the same speed, as in this technical diagram:
The fact that the treadmill is connected to the plane guarantees that the treadmill will be going in the opposite direction of the plane at the same grounspeed as the plane, whatever that is. Clearly, from this scenario, the plane moves forward from the thrust generated by the engines, even though the treadmill is moving backward at the same speed.
Now everyone shut up.
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12-15-2005, 01:34 PM #64
Think about what happens if I'm on the treadmill, you're pulling, and the thing is running.
Then you let go.
I go flying backwards.
That force that you exert on me with the rope is equal to the force exerted through the wheels by the treadmill.It's idomatic, beatch.
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12-15-2005, 01:35 PM #65
To clarify my position:
The plane will FALL off the front of the conveyor - it will NOT "take off".
edit:
1.)assuming the conveyor actually ends.
2.)for the love of God and all that is right and good: It doesn't matter how fast the damn wheels are spinning.Last edited by EPSkis; 12-15-2005 at 01:38 PM.
We've got to pause and ask ourselves: How much clean air do we need? ~ Lee Iacocca
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12-15-2005, 01:36 PM #66Registered User
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Originally Posted by Dr. SendElvis has left the building
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12-15-2005, 01:36 PM #67Originally Posted by Cornholio
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12-15-2005, 01:39 PM #68
I'm done arguing about this, actually, because there's some drastic misunderstanding taking place somewhere.
In my mind, and using the free-body diagrams I've sketched, there is no way the plane ever moves forward.
This is largely because I believe that the problem states that the treadmill pushes the plane back to match the force generated by the engines, and therefore the sum of the forces on the plane is Zero.
F=MA
There is no F.
There is no A.
There is no A, there is no Delta-V, so there is no V, so there is no airflow.
No airflow, no lift.It's idomatic, beatch.
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12-15-2005, 01:39 PM #69
I feel for you Beaver its like talking to a brick wall..
lets try this again..
say you are skiing switch, and have a big rocket pack.. then right under your skis a slab releases, you in turn ignite your rocket engine, tht has say 1000pounds of thrust.. what happens?
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12-15-2005, 01:43 PM #70Originally Posted by Cornholio
I do agree that without sufficient airflow, the plane will not lift off.We've got to pause and ask ourselves: How much clean air do we need? ~ Lee Iacocca
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12-15-2005, 01:43 PM #71Originally Posted by Cornholio
Originally Posted by The Big One
As you can see, it only matches the speed, not the force.
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12-15-2005, 01:43 PM #72Originally Posted by dubuIt's idomatic, beatch.
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12-15-2005, 01:45 PM #73Originally Posted by Cornholio
so the force applied on the plane is not the force of the tread mill..
it is the force of the coefficient of friction in the bearings,
for example
what would happen if you had a car (no engine no tranny just wheels)with wheel bearings with a coefficient of friction of 0, ie no friction. and the treadmill started to move.. the car would not move..
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12-15-2005, 01:46 PM #74
Cornholio, what is your frame of reference? Where does the treadmill's speed come from? The speed of the wheel compared to the treadmill or the speed of the aircraft as a whole from a stationary point (say, the control tower).
I've concluded that DJSapp was never DJSapp, and Not DJSapp is also not DJSapp, so that means he's telling the truth now and he was lying before.
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12-15-2005, 01:47 PM #75Originally Posted by EPSkis
The treadmill MUST push the plane back.'
Velocity is all about force. The problem specifies speeds/velocities, but if you think about them as the result of forces, it's easier to see.It's idomatic, beatch.
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